[slg]

>It's interesting to me that implicit in your argument is that the corporation has some sort of "prime" speech right that users do not,

No I'm not. Both have the same free speech. Except the corporations speech is being restricted by the government while the user's speech is being restricted by a private corporation. Only one of those is a First Amendment issue.

>We already have tons of laws that restrict what businesses can do, that would obviously restrict speech - like banning discrimination.

Discrimination is usually action and not speech. It is someone being fired, promoted, not hired, or just generally being treated differently. It generally takes for discriminatory speech to venture into harassment or a hostile environment before the government would step in.

>The law does not, in fact, dictate what private businesses can say. It gives them a list of things they cannot say

How are these not the same thing? Telling someone they can't do something is inherently telling them what they can do.

[salawat]

>Except the corporations speech is being restricted by the government while the user's speech is being restricted by a private corporation.

Government is of, by and for the People. That Corporation is composed of the People which the Government is of and for, and through which the legal fiction is granted legitimacy.

As far as I'm concerned, corporations are de facto extensions of Government.

[slg]

Everyone is entitled to their own opinions, but I don’t think this viewpoint is supported by any established law at least as far as I’m aware.